Alpha-olefins, especially those containing 6 to 20 carbon atoms, are important items of commerce. They are used as intermediates in the manufacture of detergents, as monomers (especially in linear low-density polyethylene), and as intermediates for many other types of products. Consequently, improved methods of making these compounds are desired. Especially desired, is a process capable of making a range of linear α-olefins such as 1-butene and 1-hexene.
Most commercially produced α-olefins are made by the oligomerization of ethylene, catalyzed by various types of compounds, see for instance B. Elvers, et al., Ed. Ullmann's Encyclopedia of Industrial Chemistry, Vol. A13, VCH Verlagsgesellschaft mbH, Weinheim, 1989, p. 243-247 and 275-276, and B. Cornils, et al., Ed., Applied Homogeneous Catalysis with Organometallic Compounds, A Comprehensive Handbook, Vol. 1, VCH Verlagsgesellschaft mbH, Weinheim, 1996, p. 245-258. The major types of commercially used catalysts are alkylaluminum compounds, certain nickel-phosphine complexes, and a titanium halide with a Lewis acid such as AlCl3. In all of these processes, significant amounts of branched internal olefins and diolefins are produced. Since in most instances these are undesirable and often difficult to separate, these byproducts are avoided commercially.